Production of artificial filaments, threads and the like



Aug. 12, 1958 v J. H. EDWARDS ETAL 2,

PRODUCTION OF ARTIFICIAL FILAMENTS, THREADS AND THE LIKE Filed May 12, 1954 United states Patent PRODUCTION OF ARTIFICIAL FILAMENTS, V

THREADS AND THE LIKE John Harold Edwards and Ernest Edward Tallis, Coventry, England, assignors to Courtaulds, Limited, London, England, a British company Application May 12, 1954, Serial No. 429,324

Claims priority, application Great Britain June 25, 1953 Claims. (Cl. 18-54) This invention relates to the production of artificial filaments, threads, fibres and the like hereinafter referred to as filaments, from viscose.

It is known that viscose filaments produced by the normal spinning, processes have a crenulated surface and a structure which consists of a skin and a core. This skin and core effect can be demonstrated by staining a cross-section of the filaments under specific conditions with selected dyestuffs. In addition to the difference in dyeing aflinity and in swelling property between the skin and core, the cellulose molecules of the skin are believed to be more highly orientated than those of the core.

The object of the present invention is to obtain modified viscose filaments which have a skin substantially thicker than is normally obtained.

According to the present invention a process for the production of artificial filaments comprises extruding viscose containing at least 0.1 millimole per 100 grams of viscose of a mercapto thiazole having the general formula where M represents hydrogen or a metal radical or a basic radical into an aqueous coagulating bath containing sulphuric acid, sodium sulphate, and zinc sulphate. If desired, the. benzene ring may be substituted, for example by a halogen or the benzene ring may be replaced by a naphthalene residue.

The preferred minimum concentration for addition to the viscose is one millimole per 100 grams of viscose and the preferred maximum concentration is 5 millimoles per 100 grams of viscose. The filaments obtained have a skin substantially thicker than normal and by adjusting the amount of mercapto thiazole added filaments with non-crenulated surfaces are obtained. The cross-sectional shape and the crenulation of the surface of the filaments is dependent on the particular mercapto thiazole being used and the quantity added to the viscose. Tests may be necessary in order to determine the quantity of mercapto thiazole necessary to give a desired cross-sectional shape and a surface free from crenulations. Metal salts of mercapto thiazoles are preferred to the ammonium or amine salts of mercapto thiazoles for carrying out the process of the present invention since the metal salts do not substantially alter the rate of ripening of the viscose. The coagulating bath preferably contains from /2 to percent of zinc sulphate.

The present invention also includes viscose containing at least 0.1 millimole per 100 grams of the viscose of a mercapto thiazole having the general formula ice where M represents hydrogen or a metal radical or a basic radical, and the benzene ring may be substituted, for example by a halogen, or the benzene ring may be replaced by a naphthalene residue.

The preferred mercapto thiazole for use according to the present invention is mercapto benzthiazole in the form of its sodium salt.

In addition to the non-crenulated surface and the substantial increase in skin thickness the filaments obtained by the process of the invention have a lower water imbibition than unmodified viscose filaments and they have a reduced gel swelling factor.

When extruding viscose according to the process of the present invention the distance from the jet at which the thread becomes neutralised is considerably increased by the presence of a mercapto thiazole in the viscose. The process of the present invention enables unripened or so-called green viscose to be spun.

The invention is illustrated by the following example, in which the percentages are by weight.

Exd mple Viscose containing 7.4 percent of cellulose, 7.0 percent of caustic soda and 1.1 percent of combined sulphur was prepared in the usual manner. 1.5 millimoles per 100 grams of viscose of the sodium salt of mercapto benzthiazole were added and the viscose was mixed for one hour. When the viscose was 48 hours old from the beginning of the mixing stage and had a salt figure of 5.7 it was ready for spinning.

The viscose was extruded through a jet having 750 holes, each 0.003 inch in diameter, into an aqueous coagulating bath containing 9.5 percent of sulphuric acid, 20 percent of sodium sulphate and 4.5 percent of zinc sulphate to give a thread of 1550 denier and 750 filaments. The length of immersion in the bath was 24 inches and the temperature of the bath was 48 C. The thread was drawn from the bath at a rate of 28 metres per minute by a godet and then passed through a dilute sulphuric acid bath maintained at a temperature of 95 C., to a second godet rotating at a higher speed than the first godet, to impart an percent stretch to the thread. The thread was collected in a centrifugal spinning box rotating at 4000 revolutions per minute. The cake obtained was washed free from acid and a suitable finish applied and dried.

The filaments had a non-crenulated surface and the filaments were been shaped in cross-section. The amount of skin was at least 50 percent greater than the amount found in filaments spun under identical conditions without the addition of mercapto benzthiazole to the viscose. Moreover the boundary between the skin and core was very diffuse.

Filaments prepared in the manner described above and filaments from unmodified viscose were stained to demonstrate the skin and core effect using the technique described in the Textile Research Journal, 1945, page 443.

In the accompanying drawings, Figure 1 shows stained cross-sections of filaments from unmodified viscose and Figure 2 the stained cross-sections of filaments spun in the presence of mercapto benzthiazole.

The bean shaped cross-section, thick skin and diffuse boundary between skin and core of the filaments of Figure 2 contrasts with the substantially circular crosssection, crenulated surface, thin skin and sharp boundary between the skin and core of the unmodified filaments of Figure 1.

What we claim is:

1. A process for the production of artificial filaments comprising extruding viscose containing at least 0.1 milli mole per 100 grams of viscose of a mercapto thiazole having the general formula Where M represents a radical selected from the group consisting of hydrogen, an alkali metal radical and a nitrogen-containing basic radical into an aqueous coagulating bath containing sulphuric acid, sodium sulphate and zinc sulphate.

3. A process for the production of artificial filaments comprising extruding viscose containing at least 0.1 millimole per 100 grams of viscose of mercapto benzthiazole into an aqueous coagulating bath containing sulphuric acid, sodium sulphate and ziucsulphate.

4. Viscose containing at least 0.1 millirnole per 100 grainsof the viscose of a mercapto thiazole having the general formula wherevM represents a radical selected from the group consisting of hydrogen, an alkali metal radical and a nitrogen-containing basic radical.

5. Viscose containing at least 0.1 rnillimole per 100 grams of viscose of mercapto benzthiazole.

References Cited in the file of this patent UNITED STATES PATENTS 2,535,044 Cox Dec. 26, 1950 2,593,466 MacLaurin Apr. 22, 1952 2,648,611 Richter Aug. 11, 1953 2,705,184 Drisch Mar. 29, 1955 2,732,279 Tachikawa Jan. 24, 1956 

1. A PROCESS FOR THE PRODUCTION OF ARTIFICIAL FILAMENTS COMPRISING EXTRUDING VISCOSE CONTAINING AT LEAST 0.1 MILLIMOLE PER 100 GRAMS OF VISCOSE OF A MERCAPTO THIAZOLE HAVING THE GENERAL FORMULA 